1. Field of the Invention
The present invention relates to a thin-film magnetic head with a narrower core width than conventionally possible for improved track density in magnetic disk devices, and to a process for its production.
2. Description of the Related Art
A conventional magnetic transducer is illustrated in FIGS. 1 and 2A-2C. FIG. 1 is a perspective view of a magnetic head slider 31, on which a thin-film magnetic head element 33 is formed and exposed on the rail side (floating side) of the slider 31. FIGS. 2A-2C are enlarged views of the portion of the thin-film magnetic head 33 in which FIG. 2A is a plan view, FIG. 2B is a cross-sectional view of FIG. 2A cut along the line I--I and FIG. 2C is a cross-sectional view of FIG. 2A cut along the line II--II.
On a substrate 11 there are formed a first magnetic yoke layer 14, a gap layer 20, an interlayer dielectric layer 18, a coil layer 17, an interlayer dielectric layer 18 and a second yoke layer 19 laminated in that order, after which there are formed an external connecting terminal and a working protection film (not shown), and then the ends of the first and second magnetic yoke layers 14, 19 are subjected to cutting and working at the I--I portion to make a thin-film magnetic head.
The portion which is cut and worked at the end (I--I portion) corresponds to the side facing the surface 41 of the recording medium (represented by the imaginary line in FIG. 2C, and is called the floating side 42. The width of the magnetic core of the magnetic head is determined by the width W of the section of the combined first magnetic yoke layer 14 and second magnetic yoke layer 19 (although a gap exists between them) which are exposed at the floating side.
According to the conventional magnetic transducer production process described above, the first magnetic yoke layer 14 and the second magnetic yoke layer 19 are pattern formed by a selective plating method with a resist mask or an ion milling method with a resist mask, and the core width is established during these steps.
Improved track density of the magnetic disk device requires that the core width be narrow, but because of restrictions on the resolving power of the resist it has been very difficult to realize a core width of 1 .mu.m or less, or narrower than the film thickness of the magnetic yoke layer (about 2-4 .mu.m).
It is an object of the present invention to provide a novel process which allows formation of magnetic yoke layers with narrow core widths, free from the restriction of the resolving power of resist masks.